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Nonthermal plasma (NTP) technology can oxidize and decompose diesel particulate matter (PM) under much lower temperatures (≤200 °C) without catalyst, showing promise for potential applications. A self-made NTP generator was used to produce NTP gas that reacted with PM at a certain reaction temperature and reaction time, and the concentration of O 3 in NTP was modified by adjusting the working parameters. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and gas chromatography-mass spectrometry (GC-MS) were used to analyze changes in the surface functional groups, component oxidation activity, removal effect, and the soluble organic fraction (SOF) of PM samples before and after processing. As the O 3 concentration increased, the effect of NTP on PM removal strengthened. PM surface functional groups can be converted from C–OH into C O under the action of NTP at high O 3 concentrations. The oxidation activity of the volatile fraction (VF) and soot in PM can be substantially improved under high O 3 concentrations. Higher O 3 concentrations resulted in increases in the number of oxygen-containing groups in the molecular formula of SOF and the ratio of components. This study provide a certain reference value for the strategy of removing PM pollutants from diesel engines and even the atmosphere. • Particulate matter was treated by NTP with various O 3 concentrations. • C C bonds in PM break and O atoms are added to the carbon chain to form C–OH. • Higher O 3 concentration promoted the conversion of C–OH into C O. • VF volatilization and soot oxidation activity were enhanced after NTP reaction. [ABSTRACT FROM AUTHOR]

Nonthermal plasma (NTP) can oxidize and decompose particulate matter (PM) of diesel engines at low temperatures (≤200°C), exhibiting good application prospects. PM samples were collected under different diesel engine loads and were oxidized using an NTP method. The volatile fraction (VF) mass fraction of the PM samples decreases under low engine loads (<70%) and increases under high engine loads (≥70%) after the NTP treatment. NTP can remove aldehyde groups in PM and weaken the volatilization of PM. A higher temperature is needed for the VF to reach its maximum volatilization rate after the NTP treatment. The relative content of the small molecules is significantly higher after the NTP treatment. [ABSTRACT FROM AUTHOR]

To reveal the effect of reaction temperature on the reduction of diesel particulate matter (PM) by non-thermal plasma (NTP) using oxygen as a gas source. The changes in the microcrystalline structure and the elemental state of PM before and after NTP oxidation at different temperatures were explored by Raman and X-ray photoelectron spectroscopy. After NTP oxidation, the disorder in the PM microcrystal structure and the amorphous carbon structure was reduced. The full width at half maximum (FWHM) of the D1 and D3 peaks decreased, and the FWHM of the G peak increased slightly. During the oxidation of PM, the carbon microcrystals grew and became restructured, and the graphitization of PM increased. After NTP oxidation, the content of O in PM increased as the reaction temperature increased, resulting in a gradual change in the binding form of O with C from C-O to C=O. The ability of temperature rise to promote the oxidation activity of NTP was gradually weakened for the thermal decomposition of NTP active substances. The microcrystalline structure and the occurrence state of C and O of PM changed with reaction temperature, indicating that the oxidizability of NTP on PM differed at different reaction temperatures. [ABSTRACT FROM AUTHOR]

• The evolution of PM in the process of NTP regeneration DPF was evaluated from the perspective of space-time. • The morphology evolution of pore deposition particles during NTP regeneration of DPF was revealed. • TG characteristic curve of EC shifted to lower temperature with promoting DPF regeneration. • The essence of NTP oxidative decomposition of PM is the process of removing carbon atoms. In this paper, diesel particulate filters (DPFs) were regenerated at a low temperature (100 °C) using a non-thermal plasma (NTP) injection system. The physical and chemical characteristics of the particles deposited at different regeneration stages, such as their macromorphology, microstructure, oxidation activity, surface functional groups, and soluble organic fraction, were analyzed. The results showed that when NTP flowed through the DPF, the deposited particles were oxidized, decomposed, and then removed from the channels. The soot cake dispersed into blocks from an initially dense morphology and gradually shrank until it disappeared. The residual ash lost the initial spherical structure of the carbonaceous particulate matter (PM). The weak part of the flocculant structure of PM broke first during the oxidation of NTP active substances and decomposed into a chain structure. As DPF regeneration proceeded, O atoms were continuously bonded into the PM to form oxidation intermediate products that contained C-O, C=O, and other functional groups, which improved the PM oxidation activity. Changes in the physical and chemical properties of PM at the DPF regeneration interface were more significant than those at the most downstream sampling position. The high carbon atom fraction in the soluble organic fraction (SOF) decreased, and the DPF regeneration by NTP involved the continuous removal of carbon atoms. [ABSTRACT FROM AUTHOR]